Biomedical subjects

P M Ruggieri

Publications and source records attributed to P M Ruggieri.

33 records · Page 2Linked to original sources

PubMed1990

Intracranial aneurysms: evaluation by MR angiography.

The purpose of this study was to compare the accuracy of a volume gradient-echo MR angiography (MRA) technique with that of intraarterial digital subtraction angiography (IA DSA) in the identification of intracranial aneurysms. The intracranial vasculature was examined in 47 patients by MRA and compared with IA DSA findings in 19 of these patients who had saccular or giant intracranial aneurysms. The remaining 28 patients, in whom no aneurysm was found, served as a control group. MRA was performed with the use of a velocity-compensated gradient-echo sequence (TR = 40-50/TE = 7-15) with a 15 degrees flip angle. The sensitivity and specificity were calculated for the evaluation of the cine 3D reconstructions (cine MRA) only, cine MRA + inspection of the individual partitions, and cine MRA + individual partitions + spin-echo studies. Of 21 aneurysms, of which three were missed in two patients, the sensitivity varied from 67% for cine MRA only to 86% for the cine MRA + partitions + spin-echo studies; of the 19 patients, among whom it was assumed that the diagnosis of any one aneurysm in a patient would lead to angiography and detection of additional aneurysms, the sensitivity varied from 73% for the cine MRA only to 95% for the cine MRA + partitions + spin-echo studies. The results of this study suggest that MRA can define the circle of Willis sufficiently to allow detection of intracranial aneurysms as small as 3-4 mm. MRA holds promise as a truly noninvasive screening examination of intracranial vasculature in patients at risk for aneurysms.

Adolescent↗

PubMed1990

Intracranial aneurysms: evaluation by MR angiography.

The purpose of this study was to compare the accuracy of a volume gradient-echo MR angiography (MRA) technique with that of intraarterial digital subtraction angiography (IA DSA) in the identification of intracranial aneurysms. The intracranial vasculature was examined in 47 patients by MRA and compared with IA DSA findings in 19 of these patients who had saccular or giant intracranial aneurysms. The remaining 28 patients, in whom no aneurysm was found, served as a control group. MRA was performed with the use of a velocity-compensated gradient-echo sequence (TR = 40-50/TE = 7-15) with a 15 degree flip angle. The sensitivity and specificity were calculated for the evaluation of the cine 3D reconstructions (cine MRA) only, cine MRA + inspection of the individual partitions, and cine MRA + individual partitions + spin-echo studies. Of 21 aneurysms, of which three were missed in two patients, the sensitivity varied from 67% for cine MRA only to 86% for the cine MRA + partitions + spin-echo studies; of the 19 patients, among whom it was assumed that the diagnosis of any one aneurysm in a patient would lead to angiography and detection of additional aneurysms, the sensitivity varied from 73% for the cine MRA only to 95% for the cine MRA + partitions + spin-echo studies. The results of this study suggest that MRA can define the circle of Willis sufficiently to allow detection of intracranial aneurysms as small as 3-4 mm. MRA holds promise as a truly noninvasive screening examination of intracranial vasculature in patients at risk for aneurysms.

Adolescent↗

PubMed1989

Intracranial circulation: pulse-sequence considerations in three-dimensional (volume) MR angiography.

The technique and feasibility of magnetic resonance (MR) angiography of intracranial vessels were studied in 35 healthy volunteers. Variations in image orientation, repetition time (TR), and flip angle were evaluated to determine their effects on flow-related enhancement. Gradient modifications--including echo time (TE), motion compensation, bandwidth, and field of view--were also studied in an effort to reduce motion-induced phase shifts. Results indicated that a FISP (fast imaging with steady precession) sequence with a TR of 50 msec, TE of 15 msec, velocity compensation in the read and section-select directions, acceleration compensation in the read direction, anisotropic volume, and a 1.25-mm partition thickness produced three-dimensional angiographic MR images that were accurate and reproducible in the depiction of the major intracranial vessels. Difficulties with field of view, persistent signal void secondary to higher-order motion, and spatial resolution remain major problems requiring additional study.

Adult↗

PubMed1989

Intracranial circulation: preliminary clinical results with three-dimensional (volume) MR angiography.

The authors assessed the clinical utility of a magnetic resonance angiography technique in the evaluation of intracranial circulation. Eighteen patients with a low likelihood of cerebrovascular disease (control group) and 40 patients with suspected cerebrovascular disease were imaged with a FISP (fast imaging with steady precession) sequence (repetition time of 50 msec, echo time of 15 msec, velocity compensation in the read and section-select directions with acceleration compensation in the read direction, 15 degrees anisotropic volume, and a 1.25-mm partition thickness). Ninety-four percent of images in the control group and 72% of images in the group with cerebrovascular disease were considered useful for diagnosis. This technique can provide accurate images of intracranial circulation and can be performed in conjunction with two-dimensional spin-echo or gradient-echo imaging. It was most useful in the evaluation of patent intracranial aneurysms, vessel displacement, and large-vessel occlusive disease. Disadvantages included limited field of view, persistent signal voids, limited spatial resolution, and inadequate depiction of lesions with slow flow.

Adolescent↗

PubMed1989

Three-dimensional (volume) gradient-echo imaging of the carotid bifurcation: preliminary clinical experience.

This study was designed to test the accuracy of magnetic resonance (MR) imaging with a FLASH (fast low-angle shot) 40 degrees volume pulse sequence by comparing it with intraarterial digital subtraction angiography (DSA) in patients with suspected carotid artery stenoses. Fifteen patients referred for evaluation of anterior circulation in cerebrovascular disease composed the pilot group. Twelve patients underwent correlative intraarterial DSA examinations. The FLASH volume sequence, with an echo time of 7.7 seconds, produced high-signal-intensity vascular images for 28 of 30 bifurcations. Of the 24 carotid bifurcations studied with DSA, 22 were depicted with MR angiography. Among the depicted bifurcations, 21 showed good correlation with the DSA images. These included four of four normal bifurcations, three of three with mild stenosis, four of four with moderate stenosis, eight of nine with severe stenosis, and two of two with occlusions. With respect to ulceration, three of four MR angiographic studies showed good correlation with DSA images. This preliminary experience indicates that the method is reproducible and capable of delineating carotid lesions in patients and that it can be performed in conjunction with conventional spin-echo imaging of the brain with only a small increase in patient examination time.

Adult↗

PubMed1985

CT evaluation of intracholecystic bile.

Computed tomography (CT) has been used to detect a variety of gallbladder abnormalities, but the accuracy of routine abdominal CT in evaluating intracholecystic bile has not been established. Forty-six patients were identified in whom abdominal CT and sonography were performed within 1 week of each other. Using sonographic results as the standard, sensitivity, specificity, and accuracy of CT gallbladder evaluation were calculated; both initial CT interpretations and retrospective review of scans were used for this analysis. In the retrospective review, visual interpretation of gallbladder images and measurement of intracholecystic bile attenuation (greater than or equal to 25 H, abnormal) were analyzed. The overall sensitivity of CT in detecting abnormal gallbladder contents ranged from 44% (bile attenuation greater than or equal to 25 H) to 63% (retrospective CT interpretation), while specificity ranged from 77% to 93%. The most common cause of high-attenuation bile in the series was sludge, a cause not previously reported. It was concluded that intracholecystic bile is poorly evaluated on routine abdominal CT, particularly because of low sensitivity in disease detection.

Bile↗

PubMedDate not supplied

Optimization of three-dimensional T1-weighted gradient-echo imaging of the cervical spine.

Various parameters of the three-dimensional (3D) T1-weighted magnetization-prepared rapid acquisition gradient-echo (MP-RAGE) sequence were evaluated to improve spatial resolution while maintaining T1 contrast and a short examination time in imaging of the cervical spine in volunteers. The most dramatic improvements in image resolution occurred by decreasing section thickness to 1.2 mm and increasing the in-plane matrix to 192 x 256, with a 230-mm field of view. The increase in imaging time due to the increased matrix was offset by the elimination of the preparation pulse and wait time, without dramatic changes in contrast-to-noise ratio or overall image quality. Optimum parameters included elimination of the preparation pulse and wait time, 12 degrees flip angle, 192 x 256 matrix, 1.2-mm section thickness, nonselective excitation (coronal acquisition), RF spoiling, and standard k-space ordering, for an examination time of 5 minutes 21 seconds.

Cervical Vertebrae↗

PubMedDate not supplied

Three-dimensional time-of-flight MR angiography with a specialized gradient head coil.

A gradient head coil has been developed, incorporating two independent gradients within the conventional body coil of the magnetic resonance (MR) system, with reduced rise times (200 microseconds) and maximum amplitudes of 37 and 18 mT/m in the z and y directions, respectively. This gradient coil was systematically evaluated by testing two-dimensional (2D) and three-dimensional (3D) time-of-flight (TOF) MR angiography sequences applied to a pulsatile flow phantom simulating a carotid stenosis and the intracranial vasculature. When standard 2D and 3D TOF MR angiography techniques were used to image the carotid stenosis model, dramatic signal loss in the stenotic segment and a large flow void distal to the stenosis were seen. The shorter (3.8 msec) absolute echo times (TEs) achievable with the gradient coil in 3D sequences substantially reduced the phase dispersion and associated signal loss in the region of stenosis. Shorter TEs alone (3.2 msec) did not minimize signal loss, and first-order flow compensation in the read and section-select directions provided further improvements (despite slightly longer TEs). Reduction of TEs in 2D sequences yielded relatively poor results regardless of the refocusing scheme or TE. This study confirms the predicted benefits of a dedicated coil with improved gradient capabilities for 3D MR angiography. The study suggests the limitations of 2D TOF MR angiography in the evaluation of severe stenoses.

Carotid Arteries↗

PubMedDate not supplied

Pulse sequence strategies for vascular contrast in time-of-flight carotid MR angiography.

A systematic evaluation in healthy volunteers of the relative efficacy of various techniques for background suppression to improve two-dimensional (2D) and three-dimensional (3D) time-of-flight magnetic resonance angiography of the cervical carotid arteries was performed. Conventional 2D and 3D FISP (fast imaging with steady-state precession) sequences with flow compensation were compared with modifications of these sequences, including a tracking saturation pulse (2D), prolonged absolute TEs for fat suppression based on T2* decay (2D and 3D), frequency-selective saturation of fat (2D and 3D), in-plane spatial saturation (2D), and magnetization transfer contrast (2D and 3D). The tracking saturation pulse and slight overlap of the excitation sections provided uniform background suppression without impairing depiction of the morphology of the cervical carotid arteries. Frequency-selective fat saturation was the most effective background suppression scheme among the 2D and 3D techniques but was occasionally compromised by local field inhomogeneities. Magnetization transfer contrast provided little suppression of stationary tissues in the neck because of the intrinsic limitations of the coil. In-plane spatial saturation yielded the highest background suppression but reduced apparent arterial diameters and could not be implemented in a 3D version. The T2* decay method not only reduced the apparent size of the vessels but also their signal intensity.

Adult↗

PubMedDate not supplied

Intracranial magnetic resonance angiography.

Intraarterial angiography remains the "gold standard" for the evaluation of the intracranial vasculature, but it carries with it the risks of local vascular damage, systemic reactions, transient neurologic deficits, permanent neurologic compromise, and even death. To date, magnetic resonance angiography (MRA) has been applied to a variety of different manifestations of intracranial vascular disease. Presently, MRA studies and flow measurement techniques serve to compliment the more traditional spin-echo evaluation of patients with small aneurysms, arterial and venous occlusions, vascular malformations, and in some cases of neoplastic vascular invasion. Practically, the limitations of these techniques must be taken into account such that the appropriate method is applied to answer a specific clinical question and the acquisition parameters are chosen to maximize the sensitivity and specificity of the study. The intent of this review is to summarize the technical approaches, clinical role, pitfalls, and potential improvements in the MRA techniques as they apply to the intracranial circulation.

Adult↗

PubMedDate not supplied

High resolution, magnetization transfer saturation, variable flip angle, time-of-flight MRA in the detection of intracranial vascular stenoses.

OBJECTIVE: Factors that restrict 3D TOF MRA are limited resolution, saturation of flow, and degree of background suppression. We evaluated MRA for intracranial stenoses by using a 3D TOF technique that minimizes these factors. MATERIALS AND METHODS: Twenty-nine patients underwent MRA and intraarterial digital subtraction angiography (DSA). The MRA studies were performed on a 1.5 T Siemens SP 4000 system. Integrated techniques applied to the conventional 3D TOF acquisition included the following: (a) 256 x 256 matrix with a 140 mm FOV and 0.9 mm slice thickness, yielding a 0.54 x 0.54 x 0.9 mm3 voxel; (b) tilted optimized nonsaturating excitation (TONE); and (c) magnetization transfer saturation (MTS). The intraarterial DSA was performed on a Siemens Angiostar system with a 1,024 x 1,024 noninterpolated matrix. The MRAs were reviewed by two neuroradiologists. Two hundred seventy-seven vessels were evaluated for a total of 806 segments. Vessel segments were evaluated with a 5 point scale. RESULTS: The estimated accuracy of MRA for detecting stenosis over all intracranial vessel segments was 0.88 +/- 0.03 and 0.89 +/- 0.02 for the two readers, respectively. The estimated accuracy ranged from 0.94 +/- 0.02 and 0.93 +/- 0.02 for detecting internal carotid artery stenosis by the two readers, respectively, to 0.65 +/- 0.17 and 0.71 +/- 0.15 for detecting distal vertebral artery stenosis. In vessels determined by catheter angiography to be stenosis-free, reader confidence at the proximal versus distal segments was similar for the internal carotid, basilar, and posterior cerebral arteries. However, for the anterior and middle cerebral arteries, one or both readers were more confident in diagnosing the proximal segment. CONCLUSION: High resolution MTS TONE 3D TOF MRA is an accurate technique for the screening of medium and large vessel intracranial stenoses.

Adolescent↗

PubMedDate not supplied

Hemorrhage detected using MR imaging in the setting of acute stroke: an in vivo model.

BACKGROUND AND PURPOSE: The treatment algorithm for acute cerebrovascular accidents has traditionally sorted these accidents as either hemorrhagic or nonhemorrhagic, and MR imaging, with its ability to allow expeditious assessment of vascular substrates and regional blood volume, is well suited for this purpose. Our purpose was to delineate the accuracy of MR imaging in acute, hemorrhagic forms of stroke during the time frame considered beneficial for intervention in an animal model. METHODS: Eighteen dogs with small, iatrogenic parenchymal, subarachnoid hemorrhage (SAH), or both were serially scanned over the initial 6-hour postictal period. Confirmatory pathologic specimens and 3-hour postictal CT scans were obtained in all animals. The MR and CT studies were then interpreted in a blinded fashion by two neuroradiologists for the presence of hemorrhage. The results were subjected to receiver operating characteristic analysis. RESULTS: MR imaging depicted acute parenchymal hemorrhage and SAH with a high degree of accuracy at 1.5 T. This finding was independent of each of the time points studied during the 6-hour window. For SAH, the MR accuracy for reader 1 was 0.86 (95% CI, 0.76-0.97); for reader 2, accuracy was 0.85 (95% CI, 0.71-0.99). The CT accuracy for the two readers was 0.42 (95% CI, 0.26-0.58) and 0.66 95% CI, 0.43-0.89), respectively. Fluid-attenuated inversion-recovery images improved the conspicuity of SAH on MR images and, along with spin-density-weighted spin-echo sequences, helped to establish the hemorrhagic nature. For parenchymal hemorrhage, the MR accuracy for reader 1 was 0.90 (95% CI, 0.81-0.99); for reader 2, accuracy was 0.93 (95% CI, 0.84-1.00). With CT, the accuracy of reader 1 was 0.91 (95% CI, 0.85-0.97) whereas for reader 2 accuracy was 0.76 (95% CI, 0.69-.83). Parenchymal hemorrhage detection and diagnosis was best with T2*-weighted gradient-echo images. CONCLUSION: MR imaging with appropriately selected sequences appears able to provide information regarding the presence (or absence) of hemorrhage in an acute stroke model requisite to the initiation of treatment.

Acute Disease↗

PubMedDate not supplied

Gd-DTPA-enhanced 3D MR imaging of cervical degenerative disk disease: initial experience.

PURPOSE: To assess whether a single enhanced T1-weighted gradient echo volume sequence, with the appropriate reformatted images, could be equivalent to a more conventional 2D set of MR sequences for the evaluation of cervical extradural degenerative disk disease (bony canal and foraminal stenosis; disk herniation). MATERIALS AND METHODS: Sixty-one patients evaluated for extradural degenerative disease by MR were imaged with a "standard" MR examination (Sagittal T1-weighted spin echo, axial low flip angle gradient echo), were then given 0.1 mmol/kg Gd-DTPA intravenously, and reimaged with either a 3D FLASH (fast low angle shot), TR 40/TE 7/1 excitation), 40 degree flip angle, acquired as 64, 2-mm sagittal partitions, or a 3D turbo FLASH (MP RAGE-magnetization prepared rapid acquisition gradient echo) (10/4/1), 10 degree flip angle acquired as 128, 2-mm coronal partitions. The volume sequences were reconstructed in the axial plane, and right and left 45 degree oblique coronal planes. The two sets of examinations (standard vs volume) were prospectively interpreted by two neuroradiologists for quality of examination, and location, type, and severity of extradural degenerative disease in a random, blinded, independent fashion. RESULTS: There was no significant difference between the standard examination and the 3D MP RAGE for central extradural disease. The 3D FLASH examination was significantly worse than the standard examination in identification of central extradural disease, with an average of 21 herniations not identified, or underestimated in size. Neither the 3D FLASH, nor the 3D MP RAGE examinations showed any significant improvement compared to the routine 2D examination for the location and severity of foraminal disease. CONCLUSION: If extradural degenerative disk disease is being evaluated, then a single enhanced 3D T1-weighted imaging sequence taking 6 minutes can be equivalent to a routine set of mixed 2D spin echo and low flip angle gradient echo sequences.

Cervical Vertebrae↗

PubMedDate not supplied

Thoracic aortic disease: evaluation using a single MRA volume series.

OBJECTIVE: Use of MRA for thoracic aortic disease (TAD) evaluation has been limited. This report describes an initial experience with TAD evaluation using a single MRA volume series. MATERIALS AND METHODS: A single volume series, based on sequential 2D TOF MRA, was acquired in 30 cases (28 with suspected TAD and 2 normals). Each series was processed using multiplanar reconstruction (MPR) and maximum intensity projection (MIP); resulting tomographic (one base and two MPR) and MIP sets were blindly interpreted by four reviewers to detect TAD and, if present, to diagnose its specific form. For cases incorrectly interpreted, the standard MR images were subsequently interpreted. RESULTS: The TAD categories included aneurysm (n = 13), dissection (n = 9), and arch anomalies (n = 5). Sensitivities were high for TAD overall (89-100%) and TAD in ascending and descending portions; sensitivities were lower for TAD of the arch (two of four reviewers > or = 90% for TAD overall and descending TAD). Specificities for TAD overall had a wider range (67-100%), but were high for ascending, arch, and descending portions (three to four of four reviewers > or = 90% for each). Sensitivities for aneurysms (69-92%) and dissections overall (67-100%) were comparable, as they were in ascending and arch portions; descending dissection was better detected than descending aneurysm (two of four reviewers > or = 90% for ascending or arch aneurysm and for descending dissection); overall specificities (88-100 vs. 81-95%) and specificities in ascending, arch, and descending portions were also comparable (three to four of four reviewers > or = 90% for both in each portion; two of four reviewers > or = 90% for dissection overall). Each reviewer achieved > or = 70% diagnostic accuracy for TAD (one of four reviewers = 85%); accuracies for each category were comparable. Interpretation of standard MR images corrected all detection and most diagnostic (> or = 63%) errors. CONCLUSION: This initial experience with conventional TOF MRA for TAD evaluation is encouraging, but it indicates the potential for advancements in data acquisition and/or postprocessing.

Adolescent↗

PubMedDate not supplied

3D MRI of the cervical spine: low flip angle FISP vs. Gd-DTPA TurboFLASH in degenerative disk disease.

The authors undertook this study to compare bright and dark CSF three-dimensional (3D) gradient-echo (GE) MR techniques to answer the following questions: Could a single Gd-DTPA enhanced T1-weighted GE volume sequence (with multiplanar reformats) be diagnostically equivalent for degenerative cervical disk disease to a standard sequence consisting of sagittal T1-weighted spin echo and axial low flip angle volume GE images (with reformatted images)? Does performing oblique coronal reformats perpendicular to the course of exiting cervical nerve roots improve diagnostic confidence over axial images alone? Thirty-one consecutive patients received a "routine" MR examination consisting of a sagittal T1-weighted spin echo and axial low flip angle volume sequence (FISP) [(35/7/5), 64 slices, 2 mm slice thickness, 192 x 256 matrix, 7.2 min]. Each patient was then given 0.1 mmol/kg Gd-DTPA intravenously, and reimaged with a T1-weighted volume GE sequence [(13/6/12), acquired as 128-1.2 mm coronal partitions, 192 x 256 matrix, 5.5 min]. Sequences were reconstructed on the standard diagnostic console in 1 mm increments. Sets of examinations (routine vs T1-weighted volume) were independently interpreted by three neuroradiologists for location, type, and severity of extradural degenerative disease. There was no strong or consistent trend for increased detection of disease by one imaging sequence over the other. For lateral disk disease, only 3% of the observations were in discordance. For disk disease, there was close agreement in the severity scores. All readers indicated that additional information was provided by the reformatted images more frequently with TurboFLASH (fast low angle shot) than with FISP. All readers indicated that increased confidence was provided by the reformatted images more frequently with TurboFLASH than with FISP. A single 3D contrast-enhanced TurboFLASH sequence is diagnostically equivalent to a set of two-dimensional T1-weighted sagittal spin echo and 3D axial low flip angle sequences for assessing the location and degree of cervical extradural degenerative disease. A screening examination of the cervical spine could be performed with a single contrast-enhanced 5.2 min study, and then relying on computer postprocessing to provide additional imaging planes.

Cervical Vertebrae↗